OVERALL OBJECTIVES OF THIS GRANT ARE: 1. To define significance of defective sulfation of lithocholate for chenodeoxycholate toxicity in the rhesus monkey; 2. To determine local toxicity of agents for physical dissolution of retained common duct stones; 3. To characterize the enterohepatic circulation of nor-chenodeoxycholic acid, and to define its effect on biliary lipid composition. SPECIFIC PROPOSALS IN THE GRANT INCLUDE: 1. Comparison of hepatotoxicity of intravenously infused lithocholylglycine, sulfolithocholylglycine, and chenodeoxycholate; 2. Determination of hepatotoxicity of chenodeoxycholic acid in the cecectomized rhesus monkey; 3. Determination of toxicity of cholate on the biliary tree (T-tube infusion); 4. Characterization of the metabolism of nor-chenodeoxycholic acid.